Antiglare film, process for producting the same, and display device using antiglare film

ABSTRACT

Disclosed is an antiglare film having excellent durability. The antiglare film is disposed on the front of a display device and comprises a transparent plastic film and, formed on the transparent plastic film, at least an antiglare layer having fine concaves and convexes on its surface, wherein the antiglare layer is formed of a transparent resin and satisfies requirements that: (1) the surface of the antiglare layer has a three-dimensional ten-point mean roughness of 0.9 μm to 3 μm; and (2) the mean spacing between adjacent profile peaks on a three-dimensional roughness reference plane is 20 μm to 50 μm.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an antiglare film which, in use,is disposed on the front of various display devices, such as liquidcrystal display devices, or an antiglare film which is durable againsttouch inputting. The present invention also relates to a productionprocess which can produce said antiglare film with high efficiency bymeans of a molding tool having concaves and convexes on its surface,preferably a molding roller. Further, the present invention relates to adisplay device comprising said antiglare film disposed on the front of aliquid crystal display device or the like.

[0003] 2. Background Art

[0004] Various display devices (=displays) for displaying static imagesor moving images according to electronic information are known, andCRTs, plasma displays, liquid crystal displays, electroluminescencedisplays and the like are currently on the market.

[0005]FIG. 1 shows an example of a liquid crystal display device 100.The liquid crystal display device 100 comprises: a liquid crystal panel101 comprising two polarizing plates 101 a, 101 a′ and a liquid crystaldisplay cell 101 b sandwiched between the two polarizing plates 101 a,101 a′; and a surface light source device 102 disposed on the underside(as viewed in the drawing) (which, in use of the liquid crystal displaydevice 100, corresponds to a side opposite to the viewer side) of theliquid crystal display device 100.

[0006] The surface light source device 102 comprises, for example, areflector plate 103, a light guide plate 104 having a dot pattern 104 aon its underside, a light diffusive film 105, a lens sheet 106, and aprotective film 107 provided in that order from the lower side.

[0007] In driving a liquid crystal display device to view images, animage of an object present behind the viewer is reflected from thescreen of the liquid crystal display, and the viewer often catches thereflected image. In particular, when there is indoor lighting equipmentand outdoor light behind the viewer, an image of the sun or the like isreflected from the display. This significantly deteriorates thevisibility of images.

[0008] A touch panel is one input means of computers. Among others, atouch panel operated on the screen of display devices is convenientbecause sites to be selected and touched can be freely prepared anddisplayed on the screen of the display devices.

[0009] Touch inputting with high frequency is causative of thedeposition of fingerprints or the occurrence of scratches, and, in thiscase, in addition, various types of durability are required of the touchpanel.

[0010] In order to prevent a catch of an image of indoor lightingequipment or the sun on the screen, a matte film prepared by coating acoating composition with organic or inorganic fine beads incorporatedtherein onto a transparent plastic film and then drying or solidifyingthe coating to form an antiglare layer has hitherto been used.

[0011] Organic or inorganic fine beads, which have hitherto been used inthe antiglare film, however, suffer from an unavoidable problem that thebeads come off in service and scratch the antiglare film. In addition,at the time of the production of the antiglare film, in coating thecoating composition with beads incorporated thereinto, unfavorablephenomena, such as occurrence of streaks or uneven coating, occur makingit difficult to provide even antiglare properties.

[0012] Further, in using the antiglare film thus obtained as a surfacematerial of a touch panel, beads, which have come off, scratches theantiglare film upon the application of pressure by a finger or a touchpen. Thus, the beads accelerate the occurrence of scratches.

SUMMARY OF THE INVENTION

[0013] Accordingly, it is an object of the present invention to solvethe problems involved in the conventional antiglare film attributable toorganic or inorganic fine beads contained in the antiglare layer, thatis, susceptibility to scratching, uneven properties, and, in the case ofthe application of the antiglare film to a touch panel, acceleratedoccurrence of scratches.

[0014] The above object of the present invention could have beenattained by forming an antiglare layer in an antiglare film whilespecifying the three-dimensional ten-point mean roughness and the meanspacing between adjacent convexes (profile peaks) in convexes andconcaves of the antiglare layer or while specifying haze in addition tothese parameters.

[0015] The antiglare film may be provided with a primer layer,preferably a primer layer containing transparent fine particles.

[0016] According to one aspect of the present invention, there isprovided an antiglare film to be disposed on a front of a displaydevice, said antiglare film comprising:

[0017] a transparent plastic film and an antiglare layer, the antiglarelayer being formed on a surface of the transparent plastic film, theantiglare layer having fine concaves and convexes on its surface,

[0018] wherein said antiglare layer is formed of a transparent resin andsatisfies requirements that:

[0019] (1) the surface of the antiglare layer has a three-dimensionalten-point mean roughness of 0.9 μm to 3 μm; and

[0020] (2) the mean spacing between adjacent profile peaks on athree-dimensional roughness reference plane is 20 μm to 50 μm.

[0021] Preferably, the antiglare film according to the first aspect ofthe present invention is disposed on the front of a display device, saidantiglare film comprising

[0022] a transparent plastic film; and, formed on the transparentplastic film, at least an antiglare layer having fine concaves andconvexes on its surface, wherein

[0023] said antiglare layer is formed of a transparent resin andsatisfies requirements that:

[0024] (1) the surface of the antiglare layer has a three-dimensionalten-point mean roughness of 0.9 μm to 3 μm; and

[0025] (2) the mean spacing between adjacent profile peaks on athree-dimensional roughness reference plane is 20 μm to 50 μm.

[0026] Preferably, the antiglare film has a total light transmittance ofnot less than 87% and a haze of 5 to 40.

[0027] Preferably, the transparent resin is a cured product of anionizing radiation-curable resin.

[0028] Preferably, a primer layer is provided between the transparentplastic film and the antiglare layer.

[0029] The primer layer may comprise transparent fine particles.

[0030] According to another aspect of the present invention, there isprovided a process for producing an antiglare film, comprising the stepsof:

[0031] providing a molding tool having on its surface concaves andconvexes, which have an inverted shape of concaves and convexes on thesurface of an antiglare layer to be formed and satisfy the followingrequirements (1) and (2), and forming an ionizing radiation-curableresin between the concave/convex mold face and the transparent plasticfilm to form a laminate (step of forming);

[0032] while maintaining the formed state, applying an ionizingradiation to the ionizing radiation-curable resin to form a curedproduct of the ionizing radiation-curable resin and, at the same time,adhering the cured product to the transparent plastic film to form anantiglare layer of the cured product with concaves and convexes, whichhave an inverted shape of the concaves and convexes on the surface ofthe molding tool, formed thereon (step of curing), and then

[0033] separating the laminate of the antiglare layer and thetransparent plastic film from the concave/convex face of the moldingtool (step of separation):

[0034] (1) the surface of the inverted concave/convex shape has athree-dimensional ten-point mean roughness of 0.9 μm to 3 μm; and

[0035] (2) the mean spacing between adjacent profile peaks on athree-dimensional roughness reference plane is 20 μm to 50 μm.

[0036] Preferably, the production process according to the second aspectof the present invention comprises the steps of:

[0037] bringing a transparent plastic film in a molding tool having onits surface concaves and convexes which have an inverted shape of fineconcaves and convexes of the antiglare layer to be formed;

[0038] placing, by coating, an ionizing radiation-curable resin betweenthe transparent plastic film and the molding tool;

[0039] applying an ionizing radiation to the ionizing radiation-curableresin to cure the ionizing radiation-curable resin and to adhere thecured product of the ionizing radiation-curable resin to the transparentplastic film to form an antiglare layer having fine concaves andconvexes on its surface; and

[0040] separating the transparent plastic film with the antiglare layerformed thereon from the molding tool,

[0041] said antiglare layer satisfying requirements that:

[0042] (1) the surface of the antiglare layer has a three-dimensionalten-point mean roughness of 0.9 μm to 3 μm; and

[0043] (2) the mean spacing between adjacent profile peaks on athree-dimensional roughness reference plane is 20 μm to 50 μm.

[0044] In the production process according to the second aspect of thepresent invention, a construction may be adopted wherein the moldingtool is a roller, the step of forming is carried out while winding thetransparent plastic film on the molding tool in a roller form, and thestep of curing is carried out on the molding tool in a roller form.

[0045] The transparent plastic film may have a primer layer formed onits side on which an ionizing radiation-curable resin is to be formed.

[0046] The primer layer may contain transparent fine particles.

[0047] According to a further aspect of the present invention, there isprovided an antiglare film produced by any one of the above productionprocesses.

[0048] According to a still further aspect of the present invention,there is provided a display device comprising any one of the aboveantiglare films disposed on the front of a display device.

BRIEF DESCRIPTION OF THE DRAWINGS

[0049]FIG. 1 is a diagram showing a surface light source device and aliquid crystal display device using an antiglare film;

[0050]FIG. 2 is a cross-sectional view of the antiglare film accordingto the present invention;

[0051]FIG. 3 is a diagram showing an embodiment of an apparatus forproducing an antiglare film; and

[0052]FIG. 4 is a diagram showing an embodiment wherein an antiglarefilm has been applied to a touch panel.

DETAILED DESCRIPTION OF THE INVENTION

[0053] As shown in FIG. 2A, an antiglare film 1 according to the presentinvention comprises a transparent plastic film 2 and, formed on one sideof the transparent plastic film 2 (upper surface in the drawing), anantiglare layer 3 having concaves and convexes 4 on its upper surface,or alternatively as shown in FIG. 2B, comprises a transparent plasticfilm 2 and, formed on the upper surface of the transparent plastic film2, a primer layer 5 and an antiglare layer 3 having concaves andconvexes 4 on its upper surface.

[0054] The concaves and convexes 4 in the antiglare layer 3 satisfyrequirements that:

[0055] (1) the surface of the antiglare layer has a three-dimensionalten-point mean roughness of 0.9 μm to 3 μm; and

[0056] (2) the mean spacing between adjacent profile peaks on athree-dimensional roughness reference plane is 20 μm to 50 μm.

[0057] The three-dimensional ten-point mean roughness in the requirement(1) is a measured value based on JIS B 0601-1994. More specifically, areference length is sampled from a profile curve of an object, and anaverage line is determined, followed by the calculation of a differencebetween the average value of the heights of five highest profile peaksand the depths of five deepest profile valleys. This difference value isregarded as the ten-point mean roughness.

[0058] Regarding the requirement (1), the three-dimensional ten-pointmean roughness of the concaves and convexes 4 is preferably in the rangeof 0.9 μm to 3 μm.

[0059] When the three-dimensional ten-point mean roughness is less than0.9 μm, the level of concaves and convexes is too small to prevent“external light reflection” wherein, for example, an image of indoorlighting equipment or the sun behind the viewer is reflected from thedisplay and, consequently, the viewer catches the reflected image. Onthe other hand, when the three-dimensional ten-point mean roughnessexceeds 3 μm, the haze is increased. Therefore, when the viewer viewsthe display through the antiglare film, the clouding level of the screenis increased and, as a result, the contrast of images is significantlydeteriorated.

[0060] In realizing images having a high contrast, the three-dimensionalten-point mean roughness is more preferably 0.9 μm to 1.3 μm.

[0061] The mean spacing Sm between adjacent profile peaks on thethree-dimensional roughness reference plane in the requirement (2) ismeasured according to JIS B 0601-1994 and, when n profile peaks withspacings S_(m1), S_(m2), S_(m3), . . . , S_(sm) exist in the referencelength, is determined as S_(m)=(1/n)×(S_(m1)+S_(m2)+S_(m3)+. . .+S_(mi)). The three-dimensional ten-point mean roughness is preferably20 μm to 50 μm. When the three-dimensional ten-point mean roughness isless than 20 μm, the image sharpness is lowered, while, when thethree-dimensional ten-point mean roughness exceeds 50 μm, the “externallight reflection” cannot be prevented.

[0062] The antiglare film according to the present invention satisfiesthe requirements (1) and (2) and, preferably, at the same time, has atotal light transmittance of not less than 87% and a haze of 5 to 40.

[0063] When the total light transmittance is less than 87%, the use ofthe antiglare film disadvantageously lowers the brightness of images. Sofar as the total light transmittance is not less than 87%, the higherthe total light transmittance, the better the results. The constructionof the antiglare film according to the present invention comprising atransparent plastic film 2, an antiglare layer 3 formed on thetransparent plastic film 2, and optionally a primer layer interposedbetween the transparent plastic film 2 and the antiglare layer 3provides a total light transmittance up to about 92%.

[0064] When the haze is less than 5, although the image sharpness isincreased, bright points randomly occur and, consequently, glare of thescreen cannot be avoided. On the other hand, when the haze exceeds 40,the image sharpness is disadvantageously lowered. The haze is morepreferably not more than 30 from the viewpoint of ensuring the imagesharpness.

[0065] In order to overcome the drawbacks of the prior art, concaves andconvexes may be imparted to the resin layer, not containing organic orinorganic fine beads for the formation of concaves and convexes, toprovide the antiglare film 1 according to the present invention.

[0066] Imparting the concaves and convexes may be carried out by theso-called “embossing method” wherein an embossing plate, preferably anembossing roller in a roller form, is pressed, optionally with heating,to a resin layer after or during the formation thereof. Preferably, amore efficient method may be adopted which comprises the steps of:providing a concave/convex mold having on its surface concaves andconvexes, which have an inverted shape of desired concaves and convexesof an antiglare layer to be formed; coating a highly curable resincomposition, such as an ultraviolet-curable resin, onto the moldsurface; covering the coating with a transparent plastic film; applyingultraviolet light to cure the ultraviolet-curable resin or the likewithin the concave/convex mold and, in addition, integrating the curedcoating with the transparent plastic film to form a laminate; and thenseparating the laminate from the concave/convex mold.

[0067] In this case, the resin composition may be coated onto thetransparent plastic film followed by the application of the assembly tothe concave/convex mold. Alternatively, a method may be used wherein theresin composition is supplied to the interface between the transparentplastic film and the concave/convex mold to simultaneously performcoating and forming. In any event, what is required here is to sandwichthe resin composition between the concave/convex mold and thetransparent plastic film.

[0068] The method wherein the resin composition is sandwiched betweenthe concave/convex mold and the transparent plastic film, is superiorparticularly in the reproducibility of the mold, to the embossingmethod. Therefore, this sandwich method is advantageous in thatcontemplated optical characteristics can be easily provided and, inaddition, a fine and hard concave/convex layer can be formed withoutposing a problem of a product, obtained by the so-called “embossingmethod,” such that the concaves and convexes of the product are returnedto an original flat state with the elapse of time.

[0069]FIG. 3 is a diagram illustrating a production process using anembossing device 10 wherein the above-described ultraviolet-curableresin or the like is used.

[0070] At the outset, a transparent plastic film 2 is unwound from left,and is supplied toward an embossing roller 12. The surface of theembossing roller 12 is an concave/convex mold face having concaves andconvexes 12 a which have an inverted shape of desired concaves andconvexes of an antiglare layer to be formed.

[0071] A coating head 13 is installed at the bottom of the embossingroller 12, and an ultraviolet-curable resin composition 14 is fed from aliquid reservoir (not shown) through a pipe 16 to the coating head 13.The fed ultraviolet-curable resin composition 14 is extruded through aslit 15, which is opened toward the upper part of the coating head 13,and is deposited onto the embossing roller 12 in its molding face havingconcaves and convexes 12 a. The deposited ultraviolet-curable resincomposition is then moved left by the rotation of the embossing roller12 (in the drawing, rotation in clockwise direction), and thetransparent plastic film 2 and an ultraviolet-curable resin compositionlayer 17 are laminated onto each other between the embossing roller 12and the nip roller 11 a on the film feed side.

[0072] Instead of this method wherein the ultraviolet-curable resincomposition 14 is deposited onto the mold face followed by lamination ofthe transparent plastic film 2 onto the coating, a method may be adoptedwherein, while winding the transparent plastic film 2 on the embossingroller 12, the ultraviolet-curable resin composition 14 is fed intobetween the transparent plastic film 2 and the embossing roller 12 tolaminate the ultraviolet-curable resin composition layer 17 onto thetransparent plastic film 2.

[0073] The laminate of the transparent plastic film 2 and theultraviolet-curable resin composition layer 17 is moved to the upperpart of the embossing roller 12, and is irradiated with ultravioletlight from an ultraviolet exposure system 18 installed above theembossing roller 12 to cure the ultraviolet-curable resin compositionlayer 17 and to adhere the cured product to the transparent plastic film2.

[0074] The laminate of the transparent plastic film 2 and the curedultraviolet-curable resin composition layer 17 is moved to the rightside of the embossing roller 12, and is separated by means of aseparation roller 11 b from the embossing roller 12. Thus, an antiglarefilm is prepared which comprises a transparent plastic film 2 and,formed on the transparent plastic film 2, concaves and convexes 3, of acured product of the ultraviolet-curable resin, which have an invertedshape of the concaves and convexes in the concave/convex mold face ofthe embossing plate.

[0075] In this case, preferably, the material of the transparent plasticfilm 2 is transparent and smooth and, in addition, does not contain anyforeign matter. Further, preferably, the transparent plastic film 2 ismechanically strong from the viewpoints of working and use applications.

[0076] Generally preferred examples of the transparent plastic film 2include films of thermoplastic resins, for example, cellulose diacetate,cellulose triacetate, cellulose acetate butyrate, polyamide, polyimide,polyethersulfone, polysulfone, polypropylene, polymethylpentene,polyvinyl chloride, polyvinyl acetal, polyether ketone, polymethylmethacrylate, polycarbonate, polyesters, such as polyethyleneterephthalate, and polyurethane.

[0077] Films of polyester resins, such as polyethylene terephthalateresins, extensively used in photographic films having an emulsion layerare preferred as the transparent plastic film 2 from the viewpoints ofmechanical strength and coatability. Cellulose triacetate and the likeare preferred from the viewpoints of high transparency, freedom fromoptical anisotropy, and low refractive index. Polycarbonate is preferredfrom the viewpoints of transparency and heat resistance.

[0078] These thermoplastic resin films are flexible and easy to handle.When there is no need to bend the material including the time ofhandling and, at the same time, when a hard material is desired, platesof the above resins, glass plates or other plates may also be used.

[0079] The thickness is preferably about 8 to 1000 μm, more preferablyabout 50 to 200 μm. In the case of plates, the thickness may exceed thisthickness range.

[0080] In order to improve the adhesion between the transparent plasticfilm 2 and a layer to be formed thereon, any one of or both the uppersurface and the lower surface of the transparent plastic film 2 may besubjected to conventional various physical and chemical treatments, suchas corona discharge treatment and oxidation treatment, or may bepreviously coated with an anchor agent or a coating material called aprimer to form a primer layer 5.

[0081] As described later, optical functions may be imparted to theprimer layer 5.

[0082] In the embodiment shown in FIG. 3, in forming the concave/convexlayer 3, an ultraviolet light-curable resin composition has been used.In this case, ionizing radiation-curable resin compositions includingelectron beam-curable resin compositions may be used.

[0083] The ionizing radiation-curable resin composition may be a mixtureprepared by properly mixing prepolymer, oligomer, and/or monomer, havinga polymerizable unsaturated bond or an epoxy group in the moleculethereof, together. Ionizing radiations applicable for curing includeelectromagnetic radiations or charged particle beams which have energyquantum high enough to polymerize or crosslink the molecule. In general,ultraviolet light or electron beam is used.

[0084] Examples of prepolymers and oligomers usable in the ionizingradiation-curable resin composition include: unsaturated polyesters,such as condensates of unsaturated dicarboxylic acids with polyhydricalcohols; methacrylates, such as polyester methacrylate, polyethermethacrylate, polyol methacrylate, and melamine methacrylate; acrylates,such as polyester acrylate, epoxy acrylate, urethane acrylate, polyetheracrylate, polyol acrylate, and melamine acrylate; and cationicallypolymerizable epoxy compounds.

[0085] Examples of monomers usable in the ionizing radiation-curableresin composition include: styrene monomers, such as styrene anda-methylstyrene; acrylic esters, such as methyl acrylate, 2-ethylhexylacrylate, methoxyethyl acrylate, butoxyethyl acrylate, butyl acrylate,methoxybutyl acrylate, and phenyl acrylate; methacrylic esters, such asmethyl methacrylate, ethyl methacrylate, propyl methacrylate,methoxyethyl methacrylate, ethoxymethyl methacrylate, phenylmethacrylate, and lauryl methacrylate; unsaturated substituted aminoalcohol esters, such as 2-(N,N-diethylamino)ethyl acrylate,2-(N,N-dimethylamino)ethyl acrylate, 2-(N,N-dibenzylamino)methylacrylate, and 2-(N,N-diethylamino)propyl acrylate; unsaturatedcarboxylic acid amides, such as acrylamide and methacrylamide;compounds, such as ethylene glycol diacrylate, propylene glycoldiacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, andtriethylene glycol diacrylate; polyfunctional compounds, such asdipropylene glycol diacrylate, ethylene glycol diacrylate, propyleneglycol dimethacrylate, and diethylene glycol dimethacrylate; andpolythiol compounds having two or more thiol groups in the moleculethereof, for example, trimethylolpropane trithioglycolate,trimethylolpropane trithiopropylate, and pentaerythritoltetrathioglycolate.

[0086] In general, one or a mixture of two or more compounds describedabove is used as the monomer in the ionizing radiation-curable resincomposition. Preferably, however, in order to impart usual coatabilityto the ionizing radiation-curable resin composition, the ionizingradiation-curable resin composition comprises not less than 5% by weightof the prepolymer or the oligomer and not more than 95% by weight of themonomer and/or the polythiol compound.

[0087] When flexibility is required of a cured product of the ionizingradiation-curable resin composition, the amount of the monomer may bereduced, or alternatively, an acrylate monomer having one or twofunctional groups may be used. When a cured product of the ionizingradiation-curable resin composition is required to have abrasionresistance, heat resistance, and solvent resistance, for example, anacrylate monomer having three or more functional groups may be used.Thus, the degree of freedom in the design of the ionizingradiation-curable resin composition is high. Here acrylate monomershaving one functional group include 2-hydroxy acrylate, 2-hexylacrylate, and phenoxyethyl acrylate. Acrylate monomers having twofunctional groups include ethylene glycol diacrylate and 1,6-hexanedioldiacrylate. Acrylate monomers having three or more functional groupsinclude trimethylolpropane triacrylate, pentaerythritol triacrylate,pentaerythritol tetraacryalte, and dipentaerythritol hexaacrylate.

[0088] A resin, which is uncurable by the application of an ionizingradiation, may also be added to the ionizing radiation-curable resincomposition to regulate properties, such as flexibility or surfacehardness, of a cured product of the ionizing radiation-curable resincomposition. Specific examples of resins include thermoplastic resins,such as polyurethane resin, cellulose resin, polyvinylbutyral resin,polyester resin, acrylic resin, polyvinyl chloride resin, and polyvinylacetate. Among others, the addition of polyurethane resin, celluloseresin, polyvinylbutyral resin or the like is preferred from theviewpoint of improving the flexibility.

[0089] When the ionizing radiation-curable resin composition is cured bythe application of light, particularly ultraviolet light,photopolymerization initiators or photopolymerization accelerators areadded to the ionizing radiation-curable resin composition. In the caseof a resin system having a radically polymerizable unsaturated group,for example, acetophenones, benzophenones, Michler's benzoyl benzoate,α-amyloxime esters, thioxanthones, benzoins, and benzoin methyl ethermay be used as the photopolymerization initiator either solely or as amixture of two or more. In the case of a resin system having acationically polymerizable functional group, for example, aromaticdiazonium salts, aromatic sulfonium salts, aromatic iodonium salts,metallocene compounds, and benzoinsulfonic esters may be used as thephotopolymerization initiator either solely or as a mixture of two ormore. The amount of the photopolymerization initiator added is 0.1 to 10parts by weight based on 100 parts by weight of the ionizingradiation-curable resin composition.

[0090] In addition, sensitizers, such as n-butylamine, triethylamine,and tri-n-butylphosphine may be used.

[0091] The following reactive organosilicon compound may be additionallyused in the ionizing radiation-curable resin composition.

[0092] For example, the first reactive organosilicon compound usableherein is represented by formula R_(m)Si(OR′)_(n) wherein R and R′ eachindependently represent an alkyl group having 1 to 10 carbon atoms. Thesubscript m of R and the subscript n of R′ are each an integer whichsatisfies a requirement represented by m+n=4.

[0093] Specific examples thereof include tetramethoxysilane,tetraethoxysilane, tetra-iso-propoxysilane, tetra-n-propoxysilane,tetra-n-butoxysilane, tetra-sec-butoxysilane, tetra-tert-butoxysilane,tetrapentaethoxysilane, tetrapenta-iso-propoxysilane,tetrapenta-n-propoxysilane, tetrapenta-n-butoxysilane,tetrapenta-sec-butoxysilane, tetrapenta-tert-butoxysilane,methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane,dimethyldimethoxysilane, dimethyldiethoxysilane, dimethylethoxysilane,dimethylmethoxysilane, dimethylpropoxysilane, dimethylbutoxysilane,methyldimethoxysilane, methyldiethoxysilane, and hexyltrimethoxysilane.

[0094] Silane coupling agents are usable as the second reactiveorganosilicon compound in combination with the ionizingradiation-curable resin composition.

[0095] Specific examples of silane coupling agents includeγ-(2-aminoethyl)aminopropyltrimethoxysilane,γ-(2-aminoethyl)aminopropylmethyldimethoxysilane,β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,γ-aminopropyltriethoxysilane, γ-methacryloxypropylmethoxysilane,N-β-(N-vinylbenzylaminoethyl)-γ-aminopropylmethoxysilane hydrochloride,γ-glycidoxypropyltrimethoxysilane, aminosilane, methylmethoxysilane,vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane,γ-chloropropyltrimethoxysilane, hexamethyldisilazane,vinyltris(β-methoxyethoxy)silane,octadecyldimethyl[3-(trimethoxysilyl)propyl]ammonium chloride,methyltrichlorosilane, and dimethyldichlorosilane.

[0096] Ionizing radiation-curable silicon compounds are usable as thethird reactive organosilicon compound in combination with the ionizingradiation-curable resin composition.

[0097] Specific examples thereof include organosilicon compounds havinga plurality of functional groups, which are reacted and crosslinked uponthe application of an ionizing radiation, for example, organosiliconcompounds having a polymerizable double bond group with a molecularweight of not more than 5,000. More specific examples of the thirdreactive organosilicon compound include functional polysilanes havingvinyl at one terminal, functional polysilanes having vinyl at bothterminals, functional polysiloxanes having vinyl at one terminal,functional polysiloxanes having vinyl at both terminals, and polysilaneshaving vinyl as a functional group or polysiloxanes having vinyl as afunctional group produced by reacting these compounds.

[0098] More specifically, the following compounds may be mentioned asthe third reactive organosilicon compound.

CH ₂ ═CH—(R ¹ R ² Si)_(n) —CH═CH ₂  (a)

[0099]

[0100] In formulae (a) to (e), R¹ and R² each independently represent analkyl group having 1 to 4 carbon atoms, and a to d and n are values thatbring the molecular weight of the compound to not more than 5,000.

[0101] Other organosilicon compounds additionally usable in the ionizingradiation-curable resin composition include (meth)acryloxysilanecompounds, such as 3-(meth) acryloxypropyltrimethoxysilane and3-(meth)acryloxypropylmethyldimethoxysilane.

[0102] In the production of the antiglare film 1 according to thepresent invention, the embossing roller 12 in a roller form has beenused in the embodiment described above with reference to FIG. 3. A flatembossing plate may be used instead of the embossing roller.

[0103] The surface having concaves and convexes of the molding tool,such as the embossing roller 12 or the flat embossing plate, may beformed by various methods, for example, sandblasting or bead-shotblasting.

[0104] In the antiglare film produced using the embossing plate formedby the sandblasting, a large number of concaves (that is, downwardprojections as viewed in section) are distributed on its surface. On theother hand, in the antiglare film produced using the embossing plateformed by the bead-shot blasting, a large number of convexes (that is,upward projections as viewed in section) are distributed on its surface.Studies conducted by the present inventors have revealed that, when themean roughness (for example, ten-point mean roughness Rz) is identical,as compared with the antiglare film having a large number of concavesdistributed on its surface, the antiglare film having a large number ofconvexes distributed on its surface has a lower haze value and is lesslikely to cause light, for example, from interior lighting equipment tobe reflected, that is, to cause the image of the interior lightingequipment or the like to be reflected from the antiglare film.

[0105] Accordingly, in the antiglare film 1 according to the presentinvention, more preferably, in addition to the above requirements, anadditional requirement should be satisfied such that the antiglare filmhas been produced by means of a molding tool having concaves andconvexes formed by the bead-shot blasting and, in the concaves andconvexes on the surface of the antiglare, the proportion of upwardprojections as viewed in section is higher than the proportion ofdownward projections as viewed in section. Further, in the productionprocess of an antiglare film according to the present invention, morepreferably, a molding tool, which has on its surface concaves andconvexes having an inverted shape of concaves and convexes in theantiglare film 1, that is, a molding tool satisfying, in addition to theabove requirements, an additional requirement such that the molding toolhas been formed by the bead-shot blasting and, in the concaves andconvexes on the surface of the molding tool, the proportion of downwardprojections as viewed in section (that is, concaves) is higher than theproportion of upward projections as viewed in section (that is,convexes), is used as the molding tool for forming concaves andconvexes.

[0106] Materials usable for constituting a molding tool having concavesand convexes include metals, plastics, and wood and composites of thesematerials. The metal is preferably chromium from the viewpoints ofstrength and low susceptibility to abrasion in repeated use. A materialprepared by plating the surface of an iron roller with chromium issuitable, for example, for economic reasons.

[0107] Particles (beads) usable for blasting include metal particles andinorganic particles, such as silica, alumina, or glass particles. Theparticle size (diameter) of these particles is preferably about 100 μmto 300 μm.

[0108] In blasting these particles against the material for the moldingtool, the particles, together with a high-speed gas, are blasted. Inthis case, the particles, except for the glass beads, may be used incombination with a suitable liquid, such as water. The use of the liquidcan realize the formation of a more stable surface shape. The combineduse of the glass beads and the liquid, however, causes aggregation ofparticles which makes it difficult to perform blasting.

[0109] Before the use of the molding tool on which concaves and convexeshave been formed, the surface of the molding tool is preferably plated,for example, with chromium from the viewpoint of improving durability inservice. This can advantageously realize film hardening and preventionof corrosion.

[0110] In the production of the antiglare film according to the presentinvention, preferably, the concaves and convexes on the surface of themolding tool has an inverted shape of concaves and convexes in theantiglare film to be formed.

[0111] Accordingly, the inverted shape in the concaves and convexes onthe surface of the molding tool for forming concaves and convexes shouldbe as specified above in connection with the concaves and convexes ofthe antiglare layer in the antiglare film, that is, should satisfyrequirements that: (1) the surface of the antiglare layer has athree-dimensional ten-point mean roughness of 0.9 μm to 3 μm; and (2)the mean spacing between adjacent profile peaks on a three-dimensionalroughness reference plane is 20 μm to 50 μm.

[0112] In use, when the antiglare film 1 according to the presentinvention is disposed, for example, by applying the antiglare film 1 toa display device on its viewer side in such a manner that the concavesand convexes on the surface of the antiglare layer 3 face the viewer,since the concaves and convexes 4 have a lens effect, light from adisplay device, such as a liquid crystal display device 101, is randomlyrefracted. As a result, there is a fear that bright points randomlyoccur and “glare” occurs on the screen.

[0113] In order to avoid the occurrence of this “glare,” a method may beadopted wherein a primer layer 5 is provided between the transparentplastic film 2 and the antiglare layer 3 and, in this case, fine organicor inorganic transparent fine particles having a diameter of about 1 μm,such as a polystyrene resin, are incorporated into the primer layer 5.The formation of the primer layer containing transparent fine particlescan provide internal light diffusion effect (=internal diffusion) whichprevents “glare.”

[0114] Transparent fine particles, which can be incorporated into theprimer layer 5, include, in addition to polystyrene resin beads, acrylicresin beads and silica beads.

[0115] Beads used have high transparency and small diameter, and, thus,the incorporation of the transparent fine particles can provide theeffect of diffusing light without sacrificing the sharpness oftransmitted image.

[0116] Preferably, the beads have a particle diameter of 1 to 5 μm andare incorporated in an amount of about 0.8 to 4 (by mass ratio) based on10 of the transparent resin constituting the primer layer.

[0117] In use, the antiglare film 1 according to the present inventionis disposed on the uppermost (in the drawing) of the liquid crystaldisplay device 100 described above in conjunction with FIG. 1.

[0118] Regarding the disposition of the antiglare film 1, the antiglarefilm 1 may be mechanically fixed. Preferably, however, a method isadopted wherein either a pressure-sensitive adhesive layer or anadhesive layer is formed on the underside of the antiglare film 1 shownin FIG. 2A or 2B (cross-sectional view) and the assembly is applied ontothe upper surface (in the drawing) of the liquid crystal display device100, generally the liquid crystal panel 101.

[0119] A polarizing plate 101 a generally has a laminate structurewherein a polarizer is sandwiched between two cellulose triacetatefilms. Therefore, when the cellulose triacetate film on the viewer sideis utilized as a transparent plastic film which is the substrate of theantiglare film according to the present invention, unlike the case wherean antiglare film is prepared separately from the polarizing plate andis formed on the polarizing plate, one layer, i.e., the plastic film,and the pressure-sensitive adhesive used at the time of forming can beomitted.

[0120] In use, the antiglare film 1 according to the present inventionmay be merely disposed on the front of display devices, such as liquidcrystal display devices, or alternatively may be disposed on the frontof a touch panel disposed on the front of display devices, such asliquid crystal display devices.

[0121]FIG. 4 is a diagram showing an embodiment wherein an antiglarefilm 1 has been applied onto the front of a touch panel 21 formed on thefront of a liquid crystal display device 100 through an adhesive layer24.

[0122] The liquid crystal display device 100 comprises a liquid crystalpanel 101 and a surface light source device 102 disposed on theunderside of the liquid crystal panel 101, and the liquid crystaldisplay device 100 shown in FIG. 4 corresponds to the liquid crystaldisplay device 100 shown in FIG. 1, except that the details of theliquid crystal display device 100 in FIG. 1 are not shown.

[0123] The touch panel 21 is prepared as follows. A first laminate of atransparent conductive layer 23, such as an indium tin oxide layer,formed on the underside of a transparent plastic film 22 is provided.Further, a second laminate of a transparent conductive layer 23′, suchas an indium tin oxide layer, formed on the upper surface of thetransparent plastic film 22′ is provided. The first laminate is put andformed on the top of the second laminate so that the transparentconductive layer 23 faces the transparent conductive layer 23′ whileinterposing a spacer 25 therebetween. In this touch panel 21, theapplication of a pressure onto the upper side of the touch panel bringsthe transparent conductive layers 23 and 23′ into contact with eachother and thus brings about an electrically conducting state and enablesinputting. This touch panel 21 is only one example, and the touch panelmay be any one so far as input can be done by pressing.

[0124] The antiglare film 1 comprises: a transparent plastic film 2; aprimer layer 5 and an antiglare layer 3 having fine concaves andconvexes 4 on its upper surface formed in that order on the uppersurface of the transparent plastic film 2; and a pressure-sensitiveadhesive layer 6 provided on the underside of the transparent plasticfilm 2.

[0125] As shown in FIG. 4, in an assembly comprising a liquid crystaldisplay device 101 and, formed on the liquid crystal display device 101in the following order, a touch panel 21 and an antiglare film 1,pressing the top of the antiglare film 1 in its predetermined selectedsite by a finger or a touch pen according to indication on the screen ofthe display in the liquid crystal display device 101 can permit inpututilizing the touch panel 21. The antiglare film 1 does notsubstantially deteriorate the visibility of the screen of displaydevices and, at the same time, has excellent durability such asexcellent surface scratch resistance and thus can be stably used for along period of time.

EXAMPLES

[0126] The present invention will be described in more detail withreference to the following examples and comparative examples.

Example 1

[0127] An iron roller was provided. Concaves and convexes were formed onthe surface of the roller by bead-shot blasting using glass beads havinga size of 100 mesh (particle diameter distribution: 106 to 150 μm). Thesurface of concaves and convexes was plated with chromium to a platingthickness of 5 μm to prepare an embossing roller.

[0128] In the bead-shot blasting, the blasting pressure, the spacebetween the blasting nozzle and the roller and the like were regulated,and the embossing roller thus obtained had a three-dimensional ten-pointmean roughness of 0.9 to 3 μm and a spacing between adjacent concaves(profile valleys) of 20 to 50 μm.

[0129] A 75 μm-thick polyethylene terephthalate resin film (stocknumber: A 4300, manufactured by Toyobo Co., Ltd.) was provided as atransparent plastic film. A composition prepared by mixing apolyurethane resin primer coating material (a medium main agent forchemical mat varnish, curing agent (XEL curing agent (D), manufacturedby The Inctec Inc.) in a mass ratio of main agent to curing agent tosolvent of 10:1:3.3 was gravure coated on the transparent plastic film,and the coating was dried to form a 3 μm-thick primer layer. The solventused was a mixed solvent composed of toluene and methyl ethyl ketone ina ratio of 1 : 1. Here the mixing ratio is by mass (the same shall applyhereinafter).

[0130] The apparatus, which has been described above with reference toFIG. 3, was provided, and an ultraviolet-curable resin (Unidic RC20-058, manufactured by Dainippon Ink and Chemicals, Inc.) was coated onthe embossing roller. The transparent plastic film with the primer layerformed thereon was laminated onto the coated embossing roller so thatthe primer layer faced the coating on the embossing roller.Subsequently, ultraviolet light was applied from an ultraviolet lightsource (D-bulb, manufactured by Fusion) to the laminate through thetransparent plastic film. Thereafter, the laminate was separated fromthe embossing roller to prepare an antiglare film provided with anantiglare layer having concaves and convexes on its surface according tothe present invention.

Example 2

[0131] An antiglare film was prepared in the same manner as in Example1, except that, in forming the primer layer, 3 parts of organic materialbeads (polystyrene resin beads, stock number: MX-130 H, manufactured bySoken Chemical Engineering Co., Ltd.) were added based on 10 parts ofthe main agent to the composition to render the primer layer lightdiffusive.

Comparative Example

[0132] A silica bead-containing ultraviolet-curable resin compositionwas coated directly on a transparent plastic film (as used in Example 1)without the formation of a primer layer by means of a gravure reversecoater. Thus, an antiglare layer having concaves and convexes was formedby coating only.

[0133] The antiglare films prepared in Examples 1 and 2 and ComparativeExample were evaluated for the following items: (1) (1a) total lighttransmittance and (1b) haze; (2) (2a) three-dimensional surfaceroughness and (2b) mean spacing between adjacent profile peaks; (3)sharpness (distinctness) of transmitted image; (4) external lightreflection preventive property; (5) antiglare property; and (6) scratchresistance. (1) (1a) The total light transmittance and (1b) haze weremeasured with a haze meter (“direct reading haze meter,” manufactured byToyo Seiki Seisaku Sho, Ltd.).

[0134] (2) (2a) Three-dimensional surface roughness and (2b) meanspacing between adjacent profile peaks were measured with a surfaceroughness meter (“SURFCORDER SE-30 K,” manufactured by Kosaka LaboratoryLtd.). Both the three-dimensional surface roughness and the mean spacingbetween adjacent profile peaks were expressed in μm.

[0135] (3) A measurement was carried out using four optical combs (fourslit widths of 0.25 mm, 0.5 mm, 1 mm, and 2 mm) according to themeasuring method for image sharpness for transparent samples accordingto JIS K 7105 6.6, and the total of the measured values was regarded asthe sharpness (distinctness) of transmitted image. The larger thenumeric value, the higher the sharpness of transmitted image. Themeasuring apparatus used was an image clarity measuring apparatus“ICP-1PD” manufactured by Suga Test Instruments Co., Ltd.

[0136] (4) In the measurement of the external light reflectionpreventive property, light was applied to the sample through a squaremask. In this case, an image clarity evaluation apparatus “MJ-RTS”manufactured by MIZOJIRI OPTICAL CO., LTD. was provided, the luminanceof the reflected image was caught in the regular reflection direction,and the light application angle was varied to determine the distributionof luminance relative to the application angle and to prepare a graphbased on the results, followed by the determination of the maximuminclination angle in the graph. In the case of a film not subjected toantiglare treatment, since the luminance rapidly increases at the lightapplication boundary portion, the angle value is substantially equal to90 degrees. The smaller the numeric value, the lower the level of theexternal light reflection and the higher the antiglare property.

[0137] (5) In the measurement of the antiglare property, the sample wasapplied to the front of a color filter in a liquid crystal displaydevice, and the surface of the sample was photographed with an imageclarity evaluation apparatus “MJ-RTS” manufactured by MIZOJIRI OPTICALCO., LTD. to determine the standard deviation of the luminance, withinthe screen, as the level of the antiglare property. The smaller thenumeric value indicating the level of the antiglare property, the lowerthe glare level.

[0138] (6) In the measurement of the scratch resistance, steel wool#0000 was provided and reciprocated on the sample while applying a loadof 2000 g to the steel wool to determine, as a numeric value indicatingthe scratch resistance, the number of times of reciprocation necessaryfor causing a noticeable scratch.

[0139] The results of evaluation for the above items (1) to (6) aresummarized in Table 1. In Table 1, the numbers in parentheses are thesame as those in the above evaluation items. TABLE 1 Evaluation itemsEx. 1 Ex. 2 Comp. Ex. (1a) Total light 89.2 88.3 87.4 transmittance (1b)Haze 12.4 25.3 8.1 (2a) Three-dimensional 0.935 0.935 1.01 surfaceroughness (2b) Mean spacing between 25.33 25.33 21.99 adjacent profilepeaks (3) Sharpness of 203.9 200.2 150.2 transmitted image (4) Externallight 72 72 30 reflection preventive property (5) Antiglare property 178 28 (6) Scratch resistance 90 90 20

[0140] The antiglare films prepared in Examples 1 and 2 are superior tothe antiglare film prepared in the comparative example in sharpness oftransmitted image and scratch resistance.

[0141] Further, in the antiglare film prepared in Example 2, theincorporation of organic material beads into the primer layer providedinternal diffusion effect and, by virtue of this, imparted an improvedantiglare property to the antiglare film as compared with the antiglareproperty of the antiglare film prepared in Example 1.

[0142] The antiglare film according to the first aspect of the presentinvention, when disposed on the front of a display device, such as aliquid crystal display device, can exhibit excellent external lightreflection preventive property and scratch resistance.

[0143] In an embodiment of the antiglare film according to the presentinvention wherein the total light transmittance of the antiglare film isnot less than 87% and the haze of the antiglare film is 5 to 40, inaddition to the above effect, an additional effect can be attained suchthat the disposition of the antiglare film on the front of a displaydevice causes substantially no deterioration in luminance of images and,at the same time, glare is less likely to occur while maintaining thesharpness of images.

[0144] In another embodiment of the antiglare film according to thepresent invention wherein the antiglare layer is formed of a curedproduct of an ionizing radiation-curable resin, in addition to the aboveeffects, an additional effect can be attained such that the antiglarefilm has excellent physical resistance, such as excellent scratchresistance, and excellent chemical resistance and, further, impartingconcaves and convexes by means of an embossing plate and curing theresin can be reliably carried out at a high speed.

[0145] In a further embodiment of the antiglare film according to thepresent invention wherein a primer layer is additionally providedbetween the transparent plastic film and the antiglare layer, theantiglare film has improved adhesion strength between the transparentplastic film and the antiglare layer.

[0146] In a still further embodiment of the antiglare film according tothe present invention wherein the primer layer contains transparent fineparticles, in addition to the above effect described just above inconnection with the provision of the primer layer, an additional effectcan be attained such that glare can be suppressed by virtue of internaldiffusion.

[0147] In the production process of an antiglare film according to thepresent invention wherein a tool having predetermined concaves andconvexes is used as a molding tool and an ultraviolet-curable resin isused as a material, the shape of the concaves and convexes in themolding tool are faithfully reproduced on the antiglare layer and, inaddition, imparting concaves and convexes by means of an embossing plateand curing the resin can be carried out at a high speed.

[0148] In an embodiment of the production process according to thepresent invention wherein the molding tool is in a roller form, inaddition to the above effect, a further effect can be attained such thatthe processing can be continuously carried out while rotating themolting tool and, thus, this constitution is suitable for the productionof an antiglare film in a continuous sheet form using a continuoustransparent plastic film.

[0149] In another embodiment of the production process according to thepresent invention wherein a transparent plastic film with a primer layerbeing formed on its side where the ionizing radiation-curable resin isto be formed, in addition to the above effect, a further effect can beattained such that the produced antiglare film has improved adhesionstrength between the transparent plastic film and the antiglare layer.

[0150] In a further embodiment of the production process according tothe present invention wherein the primer layer contains transparent fineparticles, in addition to the above effect, a further effect can beattained such that the produced antiglare film is improved in antiglareproperties by virtue of internal diffusion.

[0151] According to a further aspect of the present invention, there isprovided an antiglare film produced by any one of the above productionprocesses.

[0152] According to a still further aspect of the present invention,there is provided a display device comprising any one of the aboveantiglare films having the above various effects disposed on the frontof a display. Therefore, this display device can have an additionaleffect attained by the antiglare film.

1. An antiglare film to be disposed on a front of a display device, saidantiglare film comprising: a transparent plastic film and an antiglarelayer, the antiglare layer being formed on a surface of the transparentplastic film, the antiglare layer having fine concaves and convexes onits surface, wherein said antiglare layer is formed of a transparentresin and satisfies requirements that: (1) the surface of the antiglarelayer has a three-dimensional ten-point mean roughness of 0.9 μm to 3μm; and (2) the mean spacing between adjacent profile peaks on athree-dimensional roughness reference plane is 20 μm to 50 μm.
 2. Theantiglare film according to claim 1, which has a total lighttransmittance of not less than 87% and a haze of 5 to
 40. 3. Theantiglare film according to claim 1, wherein the transparent resin is acured product of an ionizing radiation-curable resin.
 4. The antiglarefilm according to claim 1, which further comprises a primer layer to beformed between the transparent plastic film and the antiglare layer. 5.The antiglare film according to claim 4, wherein the primer layercomprises transparent fine particles.
 6. A polarizing plate comprisingthe antiglare film according to any one of claims 1 to
 5. 7. A displaydevice comprising the polarizing plate according to claim 6 disposed onthe front of a display.
 8. A liquid crystal panel for a display device,comprising: two polarizing plates, the liquid crystal display cell beingsandwiched between the two polarizing plates, at least one of thepolarizing plates being the polarizing plate according to claim
 6. 9. Adisplay device comprising the liquid crystal panel according to claim 8and a surface light source device disposed on the underside of theliquid crystal panel.
 10. A display device comprising the antiglare filmaccording to any one of claims 1 to 5 disposed on the front of adisplay.
 11. A display device comprising a touch panel and the antiglarefilm according to any one of claims 1 to 5 formed in that order on thefront of a display.
 12. A process for producing an antiglare film,comprising the steps of: bringing a transparent plastic film in amolding tool having on its surface concaves and convexes which have aninverted shape of fine concaves and convexes of the antiglare layer tobe formed; placing an ionizing radiation-curable resin between thetransparent plastic film and the molding tool; applying an ionizingradiation to the ionizing radiation-curable resin to cure the ionizingradiation-curable resin and to adhere the cured product of the ionizingradiation-curable resin to the transparent plastic film, thereby formingan antiglare layer having fine concaves and convexes on its surface; andseparating the transparent plastic film with the antiglare layer formedthereon from the molding tool, said antiglare layer satisfyingrequirements that: (1) the surface of the antiglare layer has athree-dimensional ten-point mean roughness of 0.9 μm to 3 μm; and (2)the mean spacing between adjacent profile peaks on a three-dimensionalroughness reference plane is 20 μm to 50 μm.
 13. The process accordingto claim 12, wherein the molding tool is in a roller form.
 14. Theprocess according to claim 12, wherein the primer layer is formed on asurface on the transparent plastic film and the ionizingradiation-curable resin is coated on a surface of the primer layer. 15.The process according to claim 12, wherein the primer layer comprisestransparent fine particles.
 16. An antiglare film produced by theprocess according to any one of claims 12 to 15.